From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- include/xen/interface/callback.h | 85 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 include/xen/interface/callback.h (limited to 'include/xen/interface/callback.h') diff --git a/include/xen/interface/callback.h b/include/xen/interface/callback.h new file mode 100644 index 000000000..c67822a25 --- /dev/null +++ b/include/xen/interface/callback.h @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: MIT */ +/****************************************************************************** + * callback.h + * + * Register guest OS callbacks with Xen. + * + * Copyright (c) 2006, Ian Campbell + */ + +#ifndef __XEN_PUBLIC_CALLBACK_H__ +#define __XEN_PUBLIC_CALLBACK_H__ + +#include + +/* + * Prototype for this hypercall is: + * long callback_op(int cmd, void *extra_args) + * @cmd == CALLBACKOP_??? (callback operation). + * @extra_args == Operation-specific extra arguments (NULL if none). + */ + +/* x86: Callback for event delivery. */ +#define CALLBACKTYPE_event 0 + +/* x86: Failsafe callback when guest state cannot be restored by Xen. */ +#define CALLBACKTYPE_failsafe 1 + +/* x86/64 hypervisor: Syscall by 64-bit guest app ('64-on-64-on-64'). */ +#define CALLBACKTYPE_syscall 2 + +/* + * x86/32 hypervisor: Only available on x86/32 when supervisor_mode_kernel + * feature is enabled. Do not use this callback type in new code. + */ +#define CALLBACKTYPE_sysenter_deprecated 3 + +/* x86: Callback for NMI delivery. */ +#define CALLBACKTYPE_nmi 4 + +/* + * x86: sysenter is only available as follows: + * - 32-bit hypervisor: with the supervisor_mode_kernel feature enabled + * - 64-bit hypervisor: 32-bit guest applications on Intel CPUs + * ('32-on-32-on-64', '32-on-64-on-64') + * [nb. also 64-bit guest applications on Intel CPUs + * ('64-on-64-on-64'), but syscall is preferred] + */ +#define CALLBACKTYPE_sysenter 5 + +/* + * x86/64 hypervisor: Syscall by 32-bit guest app on AMD CPUs + * ('32-on-32-on-64', '32-on-64-on-64') + */ +#define CALLBACKTYPE_syscall32 7 + +/* + * Disable event deliver during callback? This flag is ignored for event and + * NMI callbacks: event delivery is unconditionally disabled. + */ +#define _CALLBACKF_mask_events 0 +#define CALLBACKF_mask_events (1U << _CALLBACKF_mask_events) + +/* + * Register a callback. + */ +#define CALLBACKOP_register 0 +struct callback_register { + uint16_t type; + uint16_t flags; + xen_callback_t address; +}; + +/* + * Unregister a callback. + * + * Not all callbacks can be unregistered. -EINVAL will be returned if + * you attempt to unregister such a callback. + */ +#define CALLBACKOP_unregister 1 +struct callback_unregister { + uint16_t type; + uint16_t _unused; +}; + +#endif /* __XEN_PUBLIC_CALLBACK_H__ */ -- cgit v1.3.1